Electrical resistance



De@ 13, 1949 H. H. MATTHEWS 2,491,1*93

ELECTRICAL RES ISTANCE Filed Dec. 5, 1945 v 2 sneets-sheet 1 f6 @mgm 252g 2x /5' /9 /9 f 4 ffm/enfer.-

Dec. 13, 1949 H. H. MATTHEWS ELECTRICAL RESISTANCE 2 Sheets-Sheet 2 Filed Deo. v5,'1945 Patented Dec. 13,y 1949 ELECTRICAL RESISTANCE Harold Herbert Matthews, Brighton, England Application December 3, 1945, Serial No. 632,402 In Great Britain November 13, 1944 Section 1, Public Law 690, August 8, 1946 Patent expires November 13, 1964 (Cl. B01-69) 2 Claims.

This invention relates to electrical resistances and refers particularly to those electrical resistances which comprise a pack of spaced and slotted plates of resistance metal. The object of the invention is the provision of an improved electrical resistance of this kind.

The invention consists broadly of an electrical resistance structure comprising a number of grids of the kind consisting of plates with slits cut into them from opposite edges alternately, said grids being clamped together in parallel spaced relation with insulating spacer elements interposed between them.

In order that the invention may be the more clearly understood a resistance structure in accordance therewith will now be described, reference being made to the accompanying drawings, wherein:

Figure 1 is a part sectional elevation of said resistance structure shown in section on line I-I of Figure 3;

Figure 2 is a perspective view of a portion of the same with certain of the parts exploded;

Figure 3 is an elevation of the same looking from the right of Figure 1 with part removed;

Figure 4 is a face View of a resistance element slightly different from the one shown in Figure 3;

Figure 5 is a section on line V-V of Figure 3.

Referring to these drawings the resistance is built up of a number of similar grids I of stamped resistance metal connected in series.

Each grid consists of a roughly rectangular sheet of resistance metal with a number of spaced cuts or slots 2 extending from each of two opposite edges nearly to the other, the spaced slots which extend from one end edge interleaving those which extend, from the other edge, so that the whole plate forms a grid having a long zigzag conductive path. The arrangement is such that the two extremities of said conductive path are located at opposite ends of the same edge of the plate, and the plate is formed with extensions 3 which continue the conductive path at its two extremities and project beyond the general line of the said edge.

A number oi such plates I are mounted in superimposed spaced relation as will be hereinafter described. The said end extensions 3 are formed with apertures 4 and each of the two sets of superimposed end extensions are coupled together by means of a bolt 5, surrounded by an insulating bush 6 passing through said apertures 4, 'said bushed bolt having circular conducting spacers 1 threaded on it, between adjacent end extensions 3.

Insulating washers 8 are provided on each bolt 5 so as to prevent alternate spacers 'I from affording electric contact between the end extensions 3 on each side as will be clear from Figure 1. Also the insulating washers 8 on the one bolt 5 are in staggered relation with respect to those on the other, and it will thus be seen that the grids are connected in series by means of the non-insulated conducting spacers 1.

The bolts 5 extend beyond the bank of grids I and are connected at their vends by nuts 9 to relatively massive supporting end plates I0. Threaded on each bolt 5 just beyond the two outermost grids I are two insulating bushes II and I2. The bush II is pressed against the end extension 3 of its adjacent grid by means of a coil spring I3 which is in compression between said bush II and a nut I4' screwed on the bolt 5. This compresses the whole of the end extensions 3, spacers 'I and washers 8 together and also compresses the insulating ibush I2 between the adjacent outermost end extension 3 and the adjacent nut 9.

In practice the end extensions 3 are enlarged at their extremities as clearly shown and the apertures 4 in them take the form of notches bifurcating the enlarged portions, and thus the bolts 5 with the spacers on them can easily be slipped into place sideways.

In Figure 3 the notches 4 for the two bolts 5 are shown differently orientated, whereas in Figure 4 they are shown similarly orientated. The reference I5 designates the terminal connecting plates for the whole series of grids. These plates as shown, are each simply threaded on to the appropriate bolt 5 between the appropriate end extension 3 and the adjacent spacer 1.

The plates I are also mounted on four bolts I6 passing through apertures I1 in said plates. Each of these bolts I6 is surrounded by an insulating bush I8 for insulating it from the plates I, and each bolt I6 also has threaded on it a number of insulating spacers I9 between adjacent plates. The apertures I1 in each plate for the four posts I6 take the form of four notches in the edges of the plate. More particularly as shown each of the edges from which the slots 2 extend have two of the notches I1 in it, the two notches in each edge being roughly in line with the two end slots 2 of the series which extend from the opposite edge.

The insulating spacers I9 on the four posts I6 are also made so as to interengage with each other and with the plates I and thus to ensure correct location. To this end each of the plates l is formed with four more apertures respectively close to the said notches I1, and the spacers I9 are extended so as to overlie these apertures 20, and each spacer I9 is formed with a projecting stud 2| on one side and with a corresponding recess 22 on the other, the arrangement being such that each stud 2| passes through the said additional aperture 29 of the plate Y| at that side and into the recess 22 of the spacer on the other side of that plate. In practice each of the said additional apertures 2i) is constituted -as shown by a notch formed in the remote side of the next slot 2, in the series extending from'theisame edge, in the direction away .from the end extension.

It will be seen that, as so far described, lnear each of those edges of each plate from which the interleaving slots 2 extend, two 'bolts I6 pass through the plate and also two studs 23| apertaining to spacers I9 threaded on said bolts. Thesebolts and studs are asshown the same distance from the respective edge of the plate l, lying on an imaginary line parallel to the said edge. Where each of these imaginary lines intersects the slots 2 in between, extending from the respective edge, the plate is formed with iurther :circular apertures 23, and further insulating spacers `24 .are provided each having a stud 24a at one side of it and a Vreces 25 on the other, and these further insulating spacers are arranged so that the stud 4Naci each one passes through one of lthe further circular apertures 23 and into the recess- 25 of the next spacer 24, justas in the case :of vthe studs 2| and recesses 22 of the spacers which are threaded-on the posts.

The series lof plates i and intervening spacers I9 and 24 terminates with spacers lI9 and 24 lat eachend of the series, and'it will be seen that 'the spacers i9 and 24 at one end v'of the series will have 'exposed studs whereas the spacers I9 :and 24 :at -the other end of the series will have exposed recesses. More particularly at one end of the series of plates and spacers, there will be `two rows-of spacers =|9 and 24 with exposed recesses and at the Yother `end lof said series there will be two -rows of spacers -|9 and 24 with exposed studs. Covering each of ythese four rows of spacers is a relatively thick and rigid metal strip 26. In the case where the metal strip covers a row-of spacers with exposed fstuds, as vat the right hand side `of Figure yl, said metal strip 2S will be formed with holes as 'shown lthrough which the studs project, and, in the case where the metal strip 26 covers a. row of spacers with exposed recesses as at the left hand side Vof Figure l and in Figure 2, said metal strip has ymetal studs 2l' (Figure 2) rivetted to it which project into said recesses. Moreover each .of these two metal strips near its two 4ends is formed with holes through which pass the two bolts |6.

The metal strips '26 at the opposite ends of the structure are clamped towards ene another vby means of nuts 28 screwed on said bolts at the fone end and 'corresponding nuts, not seen, at the other end. Betweenthe nuts 28 and the metal strips 26 coil springs 29are compressed.

The said four bolts i6 are rigidly secured at their ends by means of nuts 30 to the aforesaid supporting Iend plates I0. To increase their rigidity the metal strips 26 may be made ol channel section as shown with the channel walls set outwardly from the pack.

The four corner spacers i9 are of oblong form `-as A'shown with rounded ends. The other spacers 2'4 are'circular.

All the insulating spacers are of ceramic material for example Steatite- It will be observed that the construction and arrangement is such that the mechanical strain applied to the spacers is relatively small.

As shown the cuts or .slots 2 are widened towards the edges of the plate I and Where said slots are not widened the metal strips between them are pressed out of the plane of the plate a1- ternately in opposite directions as clearly shown and 'thus there is no danger of adjacent strips making contact with each other.

I claim:

l. An electrical 'resistance structure comprising a series of grid plates with slots formed therein from opposite edges, said grid plates being in parallel spaced relation, clamping plates parallel to said grid plates located on the outside of the two outer vvgrid plates of the series, a plurality of inl dividual insulating spacer elements between each adjacent pair 'of grid plates and between feach outer grid plate fand the adjacent clamping plate, each individual spacer element being for-med with a stud projecting from one side fand with a1re l cess inthe opposite side, -a clamping plate Ion the outside of one of the outer grid plate 'being provided with projecting studs v'and rva yclamping plate on the outside of the other outer grid plate being formed with apertures, each spacer element be tween grid plateshavingits stud passing through an aperture in an adjacent grid plate and tinto a recess in a spacer element on `the other side lof said grid plate, each spacer element between the iirst named clamping plate and the adjacent outer grid plate having Vits recess in engagement with va stud of said clamping plate and fits stud passing through Yan aperture 'in 'said :adjacent outer grid plate and into the recess 'of va lspacer element on the other side lof 'said grid pl'ate,fand each spacer element between the second named clamping plate and the adjacent outer -grid plate having its recess engaged bythe stud of vaspaoer element on the other side ol sai'douter grid plate passing through an aperture insaid grid plate'and having its stud in engagement in an. aperture of said clamping plate, said spacer elements 4bei-ng located by said studs, recesses and 'apertures'and being without bolts passing 4through them, :and means for drawing vthe yclamping Vplates to-ward one another and thereby clamping the :grid plates and lspacer elements.

2. An electrical resistance structure `compr-ising a series of grid plates with'slotsformed therein from opposite edges, said grid plates being in parallel spaced relation with 'the edges from which the slots extend in vsuperinfip'osed relation, four elongated clamping plates parallel `to -said grid ,plates located on the outside of the two outer grid plates Vof the series vrespectively alongside .the four edges of said two outer .grid .plates from which the slots extend, -two rows of individual spacer elements between each adjacent pair of grid plates, each of vsaid rows extending .alongside the grid plate edges from which theslots vare extended, a row of individual spacer elements between each clamping plate Aand the Iouter grid plate adjacent thereto, each individual spacer element lbeing' formed with-a stud projecting from one side and with a vrecess in the opposite side, two of said clamping Yplates `being provided each with Va row of projecting studs, andthe other 'two of said yclamping plates :being provided v:each with a row of apertures, each f's-pacer element between the adjacent grid plate having its stud through an aperture in an adjacent grid plate and into a recess in a spacer element on the other side of said grid plate, each spacer element between a studded clamping plate and the adjacent outer grid plate having its recessin engagement with a stud of said clamping plate and its stud passing through an aperture in said acljacent outer grid plate and into the recess of a spacer element on the other side of said grid plate, and each spacer element between an apertured clamping plate and the adjacent outer grid plate having its recess engaged by the stud of a spacer element on the other side of said outer grid plate passing through an aperture in said grid plate and having its stud in engagement in an aperture of said clamping plate, said spacer elements being located by said studs, recesses and apertures and without bolts passing through them, and means for drawing the clamping plates toward one another and thereby clamping the grid plates and spacer elements.

HAROLD H. MATTHEWS.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS 

